Mutli-functional photometer with movable linkage for routing optical fibers

ABSTRACT

A multi-functional photometer includes a scanning mechanism having a housing (10) that bears a movable linkage (12). The linkage is coupled to an optical scanning head (18) and incorporates optical fibers for transmitting radiant energy to and from the scanning head. The arm comprises a C-shaped &#34;elbow&#34; member (14), pivotally attached to a &#34;shoulder&#34; member (16). In turn, the &#34;shoulder&#34; member of the arm is pivotally connected to the housing. Dynamic couplings join the optical fibers such that the shapes thereof remain fixed regardless of the orientation of the arm. The housing further incorporates a Cartesian-coordinate table (20) for positioning the scanning head with respect to a microplate (22) that contains a plurality of analyte samples.

FIELD OF THE INVENTION

The present invention relates to the field of spectroscopy, particularlyto a multi-functional photometer capable of measuring light absorbance,fluorescence, and luminescence of a sample.

BACKGROUND OF THE INVENTION

In biological research, it is often necessary to assay samples forcontent of various chemicals, hormones, and enzymes. Spectroscopy, whichis the measurement and interpretation of electromagnetic radiationabsorbed or emitted when the molecules, or atoms, of a sample move fromone energy state to another, is widely utilized for this purpose.Currently, the most common spectroscopic techniques pertain tomeasurements of absorbance, fluorescence, and luminescence.

Chemical analyses with absorption spectroscopy allow one to determineconcentrations of specific components, to assay chemical reactions, andto identify individual compounds. Absorbance measurements are mostcommonly used to find the concentration of a specific composition in asample. According to Beer's law, for a composition that absorbs light ata given wavelength, the total absorbed quantity of such light is relatedto the quantity of that composition in the sample.

Fluorescence, in turn, is a physical phenomenon based upon the abilityof some substances to absorb and subsequently emit electromagneticradiation. The emitted radiation has a lower energy level and a longerwavelength than the excitation radiation. Moreover, the absorption oflight is wavelength dependent. In other words, a fluorescent substanceemits light only when the excitation radiation is in the particularexcitation band (or bands) of that substance.

For fluorescence measurements, fluorescent dyes called fluorophores areoften used to "tag" molecules of interest, or targets. After beingirradiated by an excitation beam, fluorophores, bonded to the targets,emit light that is then collected and quantized. The ratio of theintensity of the emitted fluorescent light to the intensity of theexcitation light is called the "relative fluorescence intensity" andserves as an indicator of target concentration. Another usefulcharacteristic is the phase relationship between the cyclic variationsin the emitted light and the variations in the excitation light, i.e.,the time lag between corresponding variations in the emission andexcitation beams.

As noted above, luminescence measurements can also be employed foranalyzing biological samples. Luminescence is the property of certainchemical substances to emit light as a result of a chemical change; noexcitation from a light source is necessary. Moreover, luminescence canbe produced by energy-transfer mechanisms that take energy of a highintensity, e.g., a radioactive emission, and transform it to energy of alow intensity, e.g., a flash of light.

At the present time, a variety of spectroscopic instruments is commonlyused in the art. A number of these instruments are designed to beutilized in conjunction with multi-site analyte receptacles called"microplates", which usually comprise one-piece structures havingmultiplicities of wells for holding analyte samples. Microplates arebeneficial since they allow simultaneous preparation of a large numberof test samples. Moreover, microplates are inexpensive, safe, sturdy,and convenient to handle. They are also disposable and can be cleanedeasily when necessary.

One instrument currently available for fluorescent analysis of samplesin microplate wells is the Cytofluor 2300 fluorometer, distributed byMillipore Corporation, Bedford, Mass. This fluorometer includes ascanning head that resides underneath the microplate and moves along thebottom face thereof to scan the sample sites. The scanning headinterfaces with the optical system of the device via a bundle of opticalfibers that transmits excitation and emission radiation.

However, the capabilities of the Cytofluor 2300 fluorometer are limitedin that it cannot perform absorbance measurements. Furthermore, themovement of the scanning head from one microplate well to anothercontinuously alters the geometrical configuration of the optical-fiberbundle that is attached to the head. Consequently, curvatures of thelight-transmitting fibers change, introducing variations in theiroptical properties. These variations create inconsistencies in readingsbetween different wells and adversely affect the repeatability, andthus, accuracy of measurements. Moreover, continuous bending of thefibers produces stresses that cause mechanical failure of the fibercores.

Additionally, to allow unrestricted movement of the scanning head,flexible plastic fibers are employed, as opposed to less pliable quartzfibers. 0n the down side, plastic fibers cannot efficiently transmitradiant energy in the ultraviolet (UV) region of the spectrum.Accordingly, the fluorometer is unable to perform measurements, such asbinding studies of certain proteins, e.g., tryptophan, sincefluorescence analyses of this type require the use of UV radiation.Furthermore, the deformation resistance of the optical-fiber bundleslows the movements of the scanning head, thus limiting the ability ofthe apparatus to perform kinetic measurements.

Another spectroscopic apparatus utilizing microplates is disclosed inU.S. Pat. No. 4,968,148 to Chow et al., 1990. Chow's device uses anoptical distributing element to selectively direct radiant energy tospecified microplate sites. One drawback of this instrument is itsinability to perform fluorescence measurements. Moreover, the largenumber of fibers unnecessarily complicates the apparatus and increasesproduction costs. Also, the light-delivery system of the instrument hasa fixed geometry that can only accommodate a microplate with oneparticular well layout. Chow's apparatus does not have the versatilityto be utilized with microplates having different configurations ofwells.

OBJECTS AND SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide amulti-functional photometer which overcomes the foregoing disadvantages,e.g., which measures absorbance, fluorescence, and luminescence of asample; which provides repeatable measurements and produces consistentreadings between different test sites; which eliminates recurringbending of optical fibers and mechanical failure thereof; which utilizesoptical radiation ranging from the ultraviolet to the infrared spectrum;which is able to carry out kinetic measurements; which can accommodatemicroplates with different well configurations; and which is relativelysimple and inexpensive to manufacture.

Another object of the invention is to supply a photometer having amovable linkage for dynamically and interconnectingly routing opticalfibers such that a constant configuration thereof is always maintainedduring operation of the photometer.

Yet another object of the invention is to provide a photometer whichperforms analyses of optical signals resulting from phenomena ofabsorbance, fluorescence, and luminescence over a range of spectralwavelengths. Further objects and advantages will become apparent afterconsideration of the ensuing description and the accompanying drawings.

In the preferred embodiment of the present invention, a multi-functionalphotometer includes a scanning mechanism having a housing that bears anarticulated movable arm. The arm is coupled to an optical scanning headand incorporates light-transmitting conduits, such as optical fibers,for transmitting radiant energy to and from the scanning head. The armcomprises a C-shaped "elbow" member, pivotally attached to a "shoulder"member. In turn, the "shoulder" member of the arm is pivotally connectedto the housing. Dynamic couplings join the optical fibers such that theshapes thereof remain fixed regardless of the orientation of the arm.

The housing further incorporates a Cartesian-coordinate table forpositioning the scanning head with respect to a microplate that containsanalyte samples. To measure absorbance, fluorescence, and luminescenceof the samples, an optical system, incorporating a plurality of lenses,filters, and sensors is utilized. Radiant energy for these measurementsis provided by a light source having a microcomputer-controlled powersupply. The same microcomputer governs the operation of the opticalsystem and the positioning table.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, where:

FIG. 1 is a schematic side view of a multi-functional photometeraccording to the present invention.

FIG. 2 is a schematic representation of an optical system utilized bythe photometer of FIG. 1.

FIG. 3 is a schematic representation of an alternative embodiment of theoptical system of FIG. 2.

FIG. 4 is a side elevational view of a movable arm of the photometerillustrated in FIG. 1.

FIG. 5 is a sectional view of an optical-fiber coupler of the photometerof FIG. 1.

FIG. 5A is a sectional view of an optical-fiber coupling provided by thecouplers such as the one shown in FIG. 5.

FIG. 6 is a sectional view of an optical scanning head of the photometershown in FIG. 1.

FIG. 7 is a top plan view of the scanning head of FIG. 6.

FIG. 8 is a sectional view of an optical-fiber integrator utilized bythe photometer of FIG. 1.

FIG. 9 is a side elevational view of the movable arm of FIG. 4 modifiedto accommodate the alternative embodiment of the optical system, shownin FIG. 3.

FIG. 10 is a block diagram illustrating the operation of the photometerof FIG. 1.

For purposes of illustration, these figures are not necessarily drawn toscale. In all of the figures, like components are designated by likereference numerals.

DETAILED DESCRIPTION

Throughout the following description, specific details, such asmaterials, dimensions, etc., are set forth in order to provide a morethorough understanding of the invention. However, the invention may bepracticed without these particulars. In other instances, well knownelements have not been shown or described to avoid unnecessarilyobscuring the present invention. Accordingly, the specification anddrawings are to be regarded in an illustrative, rather than arestrictive, sense.

FIG. 1 shows a schematic side view of a multi-functional photometeraccording to the present invention. The photometer comprises a housing10 that pivotally supports a movable arm 12, containing a C-shaped rigid"elbow"member 14 and a rigid "shoulder" member 16. The housing isapproximately 21 cm tall, 18 cm wide, and 26 cm long. Arm 12incorporates a plurality of optical fibers and is coupled to a firstscanning element, e.g., an optical scanning head 18. The structure ofarm 12 and the coupling mechanism of the optical fibers will bedescribed fully in the ensuing section of the specification.

Scanning head 18 is rotationally attached through bearings 136 and 138to a conventional positioning table 20, e.g., the Pen Plotter table,manufactured by Hewlett Packard Company of Palo Alto, Calif. Positioningtables like the Pen Plotter are often computer controlled such that thecomputer specifies X and Y coordinates of a point to be located by themechanism of the table. Table 20 positions head 18 with respect to amicroplate 22 that holds samples to be analyzed in a multiplicity ofanalyte wells, such as a well 23. As illustrated in FIG. 1, both table20 and microplate 22 are supported within housing 10.

The optical system of the apparatus, described in reference to FIGS. 1and 2, has a light-delivering assembly, a light-gathering assembly forabsorbance measurements, and a light-gathering assembly for fluorescenceand luminescence measurements. The light-delivering assembly includes alight source 24; a collimating lens 26; a plurality of bandpass filters28, individually selectable by means of a rotary filter wheel 30; a beamsplitter 32; a focusing lens 34; optical fibers 36, 38, and 40 arrangedin series; and a collimating lens 42. Light source 24 typicallycomprises a xenon arc lamp, energized by a DC power supply 44, e.g., ofType 5 manufactured by Mimir Corporation of Sunnyvale, Calif. The powersupply is controlled by a microcomputer 46, which also governs thepositioning operations of table 20 and the functions of the opticalsystem, e.g., the angular position of filter wheel 30. Microcomputer 46may have, for example, a 80286 microprocessor from Intel Corporation ofSanta Clara, Calif.

The light-gathering assembly for absorbance measurements comprises areference-signal photodetector 48, a focusing lens 50, and a secondscanning element for collecting light transmitted through microplate 22,e.g., a photodetector 52. Photodetectors 48 and 52, which convertelectromagnetic radiation into electric current, may be implemented asphotovoltaic cells. After being converted to a digital format by ananalog-to-digital converter (not shown), the outputs of photodetectors48 and 52 are analyzed by microcomputer 46.

The light-gathering assembly for fluorescence and luminescencemeasurements includes optical pick-up fibers 54, 56, and 58, arrangedside-by-side. The pick-up fibers are collectively coupled to alight-transmitting fiber 60, which interfaces with an optical fiber 62.Upon exiting fiber 62, light passes through a collimating lens 64; oneof a plurality of bandpass filters 66, selectable by turning a rotaryfilter wheel 68, which is computer-controlled; and a focusing lens 70.Lens 70 focuses the optical signal on a photodetector 72, whose outputis then digitized and processed by microcomputer 46. In an alternativeembodiment of the optical system (FIG. 3), a light-dispersing device 74replaces filter wheel 68 for fluorescence and luminescence measurements.Moreover, instead of being directed to photodetector 52, the opticalsignal, transmitted through one of a multiplicity of microplate wells23, is channeled to the light-dispersing device through lens 50 viasequentially coupled optical fibers 76, 78, and 80. Light-dispersingdevice 74 comprises a diffraction grating that disperses incomingoptical radiation into component wavelengths, which are gathered atphotodetector 72. Thus, analyses of optical signals resulting fromphenomena of absorbance, fluorescence, and luminescence can be performedover a range of wavelengths, rather than at a narrow spectral bandwidthprovided by an individual filter. Consequently, valuable additionalinformation may be learned about the properties of analyte samples beingstudied.

MOVABLE ARM FOR ROUTING OPTICAL FIBERS

Movable arm 12, generally illustrated in FIG. 1, is shown in greaterdetail in FIG. 4. The arm comprises an articulated linkage havingmovably coupled members 14 and 16. Member 16 is a substantiallyrectangular structure having mounting protrusions 82, 84, 86, and 88.The protrusions contain openings accommodating optical-fiber couplers90, 92, 94, and 96, respectively. The couplers are fixed inside theopenings with threaded fasteners, e.g., set screws 98.

As shown in FIG. 5, each of the couplers of the type described above,for example coupler 96, contains a centrally-disposed through bore 99,having a radial dimension that is uniform along the entire length of thebore. Moreover, each coupler has two distinct cylindrical surfaces 101and 103. Surface 101 has a larger radial dimension then surface 103 anddefines the end of the coupler where an optical fiber is to be inserted.

FIG. 4 further illustrates the pivotal attachment of member 16 tohousing 10 by means of a bearing assembly 100, which includes a pair ofring bearings 102 and 104 that support couplers 90 and 92. Bearings 102and 104 are retained within collars 106 and 108, respectively, wherecollar 108 is integral with housing 10. The two collars are rigidlyinterconnected by a hollow cylindrical sleeve 110. The above-describedstructure allows member 16 to pivot with respect to housing 10 about anaxis defined by the vertical symmetry axis of sleeve 110.

Similarly, bearings 112 and 114 allow member 16 to pivotally supportC-shaped member 14. The C-shaped member has a hinge portion 116, whichis rigidly attached to one end of a cylindrical hollow sleeve 118 with aset screw 120. The inner races of bearings 112 and 114 are mounted oncouplers 96 and 94, respectively. The outer race of bearing 114 sustainsportion 116, while bearing 112 is inserted into the second end of sleeve118. This structure permits member 14 to pivot with respect to member 16about an axis defined by the vertical symmetry axis of sleeve 118.

Member 14 further includes parallel beams 122 and 124, integrallyconnected by a shank 126. Beam 122 contains a cylindrical bore 128 thataccommodates scanning head 18 (first scanning element) whereas beam 124bears the second scanning element comprising lens 50 and photodetector52. The second scanning element, which is collinear with the scanninghead, is located with respect to beam 124 with dowel pins (not shown)and is attached to the beam with screw-type fasteners.

Head 18 comprises a substantially cylindrical casing 130 that isretained inside bore 128, e.g., with a set screw 131. Casing 130 has athrough longitudinal opening 132 that houses an optical-fiber coupler134 at one end and lens 42 at the other. A set screw 135 anchors coupler134 within opening 132. Ring bearings 136 and 138 are mounted on flangesdefining bore 128 for rotationally coupling head 18 to positioning table20 (schematically shown in FIG. 1). Casing 130 further comprises threethrough cavities 140 (only one of which is shown in FIG. 4),symmetrically arranged around opening 132 and having an angle ofapproximately 12° with respect to the vertical axis of the casing.

Cavities 140 contain ends of optical fibers 54, 56, and 58, which may beused to pick up fluorescent emissions. Due to the oblique arrangement ofcavities 140, these fibers are less likely to receive excitation fromfiber 40. The opposite ends of fibers 54, 56, and 58 are routed via alateral opening in sleeve 118 into an optical-fiber integrator 142,which contains a through central opening for housing the fibers.Integrator 142 is anchored by a set screw 146 inside a through centralbore of spacer 148, the latter being fixed by the same screw withinsleeve 118. The integrator is positioned such that its central openingis collinear with the central bore of coupler 96 to allow exchange ofradiant energy between fiber 60 and fibers 54, 56, and 56.

A set screw 150 secures an optical-fiber coupler 152, identical tocouplers 90, 92, 94, 96, and 134, within a through opening in hingeportion 116 such that the bores of couplers 94 and 152 are collinear.The above-described couplers may be made of an opaque material, such asaluminum. Each coupler is about 6.1 mm long and the radial dimension ofthe longitudinal central bore is approximately 0.5 mm. The opticalfibers inserted inside the couplers, e.g., couplers 94 and 152,completely occupy central bores 99 such that the ends of the fibers areflush with the end-faces of the couplers, as shown in FIG. 5A. Thefibers are typically retained inside the couplers by friction or with anadhesive placed along the fiber shafts such that during insertion of thefibers into the couplers the end-faces of the fibers are not coveredwith the adhesive.

Casing 130 of scanning head 18 is illustrated in greater detail in FIGS.6 and 7. A sectional view of the casing (FIG. 6) depicts theconfiguration of opening 132, which comprises a coupler portion 154 anda lens portion 156. Portion 154 houses coupler 134 (shown in FIG. 4)while portion 156 is used for mounting collimating lens 42 (shown inFIGS. 1 and 4). The path of radiant energy through the casing isrestricted by a neck aperture 158 formed in casing 130. Inclined,through cavities 140, only one of which can be shown in the sectionalview of FIG. 6, surround opening 132. The cavities contain opticalfibers, such as fiber 54, and are equidistant from each other (FIG. 7).The fibers occupy the full length of cavities 140 such that the ends ofthe fibers are flush or only slightly recessed with respect to theendface of casing 130. The casing may be made of an opaque material,e.g., aluminum, and is approximately 17.5 mm long. Neck aperture 158restricts the diameter of the light path to approximately 2.0 mm.

The construction of optical-fiber integrator 142 is described in detailwith reference to FIG. 8. Integrator 142 has a generally cylindricalshape and a centrally-disposed aperture 144 containing an optical fibersegment 159 that is secured inside the aperture, e.g., by an adhesive.Segment 159 completely fills aperture 144 such that one end of thesegment is flush with the endface of integrator 142. The integrator alsopossesses a cylindrical bore 160 that accommodates the ends of opticalfibers 54, 56, and 58, which are fixed inside the bore. Bore 160 has aslightly greater radius than aperture 144 and is joined therewith at aflange 162 so that fiber segment 159 is contiguous with fibers 54, 56,and 58. To maximize light transmission between fiber segment 159 andfibers 54, 56, and 58, the difference in the radial dimensions ofaperture 144 and bore 160 is minimal. Thus, fibers 54, 56, and 58 eachhave a smaller diameter than segment 159 such that their combinedcross-sectional area is approximately the same as that of segment 159.In turn, the diameter of segment 159 is the same as those of fibers 36,38, 40, 60, and 62. To facilitate the insertion of the optical fibersinto the integrator, an opening 164, which possesses a greater radiusthan the bore, is formed collinearly with the latter. Opening 164 has acountersink 165 for gradually guiding the ends of the optical fibersinto bore 160. Integrator 142 may be made of an opaque material, e.g.,aluminum. The integrator is about 25 mm long, aperture 144 is about 2.3mm in diameter, and bore 160 has a diameter of approximately 2.3 mm.

Referring once again to FIG. 4, the coupling of the optical fibers isnow further described. One end of fiber 40 is secured inside the bore ofcoupler 134 while the other end is routed inside coupler 152 via alateral opening within sleeve 118. Similarly, the ends of fiber 38 areretained inside couplers 92 and 94. Fiber 60 and couplers 90 and 96 arearranged identically. A space of about 0.2 mm is provided between thejuxtaposed faces of couplers 94 and 152 as well as between those ofcoupler 96 and integrator 142 for allowing member 14 of the movable armto freely pivot with respect to member 16.

To link fibers 38 and 60 with the optical system described in theprevious section of the specification, optical fibers 36 and 62,interfacing with the rest of the optical components, are routed intosleeve 110 via a lateral opening therein. The ends of these fibers aresupported within couplers 107 and 109 anchored inside collars 106 and108 such that the fibers 36 and 62 are collinear with fibers 38 and 60,respectively. A distance of approximately 0.2 mm separates thecontiguous faces of couplers 90 and 107 as well as the faces of couplers92 and 109. This permits member 16 to pivot freely with respect tohousing 10. Fibers 38, 40, and 60 are approximately 20 cm long and 1.0mm in diameter. Fibers 54, 56, and 58 each have a diameter of about 0.8mm and a length of approximately 20 cm. In one embodiment of theinvention, all optical fibers are made of quartz, thereby allowingtransmission of ultraviolet light.

As noted above, the juxtaposed faces of the respective couplers (e.g.,94 and 152) are aligned such that the ends of their respective fibersare collinear and contiguous to maximize light transmission between thefibers. The alingment of the fibers is illustrated in FIG. 5A.

DYNAMIC OPTICAL-FIBER COUPLING PROVIDED BY MOVABLE ARM

The operation of dynamic optical-fiber couplings provided by arm 12 cannow be outlined with reference to FIGS. 4 and 5A.

As table 20 positions scanning head 18 at various wells of themicroplate, member 14 pivots on bearings 112 and 114 relative to member16. In turn, member 16 pivots relative to housing 10 on bearings 102 and104. Specifically, as member 14 rotates with respect to member 16,fibers 40, 54, 56, and 58 move together therewith without twisting orbending. Optical contact between fiber 40 and fiber 38 is maintainedthrough the dynamic coupling provided by couplers 152 and 94 regardlessof the angular relationship between members 14 and 16. Optical contactbetween fiber 60 and pick-up fibers 54, 56, and 58 is maintained in asimilar manner with the use of coupler 96 and integrator 142. Moreover,the integrator allows the system to relay the optical signals of aplurality of fibers into a single fiber, thus providing a simple, yetextremely sensitive optical arrangement for performing fluorescencemeasurements.

Fibers 38 and 60 are also dynamically coupled with fibers 36 and 62,respectively, since couplers 90 and 92 rotate relative to housing 10 inrespective bearings 102 and 104, whereas fibers 36 and 62 remainstationary in couplers 109 and 107, which are anchored to collars 106and 108 of housing 10.

Thus, bending and twisting of optical fibers is eliminated, guaranteeingrepeatability and consistency of measurements and preventing mechanicalfailure of fiber cores due to cyclical bending stresses. Moreover, sincecompliance of optical fibers does not affect the movement of scanninghead 18, stiffer quartz fibers can now be employed to allow transmissionof ultraviolet radiation, which may be useful in certain types offluorescence measurements. Also, the absence of bending resistance inthe fibers permits the positioning table to move the scanning headquickly enough to perform kinetic measurements.

Additionally, parallel beams 122 and 124 of member 14 allow the systemto position lens 50 and photodetector 52 collinearly with respect toscanning head 18 so that absorbance measurements (typically done bypassing radiant energy from fiber 40 to detector 52 through an analytesample) can be performed together with fluorescence and luminescenceassays. Furthermore, the scanning head orients the ends of opticalfibers 54, 56, and 58 obliquely to its longitudinal axis to prevent thefibers from picking up optical noise from the edges of microplate wellsduring fluorescence and luminescence measurements. Fibers 54, 56, and 58are designed to pick up (receive) flourescence and luminescenceemissions and fiber 40 is designated to provide the excitation light inthe case of fluorescence. In this manner, fluorescence and luminescencemeasurements are taken above the microplate rather than through it.

MOVABLE ARM MODIFIED TO ACCOMMODATE ALTERNATIVE EMBODIMENT OF OPTICALSYSTEM

FIG. 9 shows a movable arm modified to accommodate the alternativeembodiment of the optical system (illustrated in FIG. 3).

In order to provide an optical connection between the second scanningelement, i.e., collimating lens 50, and light dispersing device 74 (FIG.3), optical fibers 76 and 78 are attached to members 14 and 16,respectively. To accommodate these fibers, mounting protrusions 170 and172 are added to member 16, whereas member 14 is formed with a secondhinged portion 174. Protrusions 170 and 172 have openings for housingoptical-fiber couplers 178 and 176, respectively. Couplers 178 and 176are anchored within their respective openings with set screws 182 and180 and accommodate ends of fiber 78 in their centrally-disposed throughbores.

Hinged portion 174 possesses an opening for housing an optical coupler184 and a bearing 186. Coupler 184 is positioned such that the throughcentral bores of couplers 178 and 184 are collinear and a distance ofabout 0.2 mm separates their juxtaposed faces. Bearing 186 housescoupler 178 and, together with bearings 112 and 114, allows member 14 topivot with respect to member 16. One end of fiber 76 is coupled to lens50, while the other end is inserted into the bore of coupler 184, whichis rigidly attached to member 14 with a set screw 188. As member 14rotates with respect to member 16, integrator 144 and couplers 152 and184 rotate together with member 14, whereas couplers 96, 94, and 178 areanchored to member 16 and remain stationary. Thus, member 14 can pivotwith respect to member 16 without deforming fibers 76, 40, 54, 56, and58.

To provide an optical interconnection between fibers 78 and 80, coupler176 is mated with a coupler 190, which is rigidly attached to housing 10and is collinear with coupler 190. A bearing 192, mounted in housing 10,supports coupler 176 and, together with bearings 102 and 104, allowsmember 16 to pivot with respect housing 10 without deforming fibers 38,60, and 78. Since lens 50 shares an optical axis with head 18, opticallycoupling the lens with light dispersing device 74 (FIG. 3) allows thephotometer to analyze optical signals, resulting from the phenomenon ofabsorbance, over a broad range of wavelengths. Thus, a morecomprehensive analysis of the analyte samples can be performed.

OPERATION OF PHOTOMETER

Operation of the photometer is described in reference to the generalsteps outlined in FIG. 10 and the apparatus shown in FIG. 1.

As the photometer is initially energized (step 200), microcomputer 46instructs power supply 44 to maintain light-source 24 in idle mode byapplying power of approximately 30 Watts to the light-source.

The microcomputer is then provided with a set of operating instructions(step 202). These contain information regarding specific measurementparameters, e.g., type of scan (absorbance, fluorescence, orluminescence--measured individually or simultaneously), number of timesto repeat the scanning cycle, various geometries of microplate-wellarrays, filter positions, duration of scanning cycle, etc.

In accordance with the instructions received in step 202, themicrocomputer selects appropriate bandpass filters 28 and 66 by rotatingfilter wheels 30 and 68, respectively (step 204). After the selection ofthe filters is completed, the microcomputer instructs the power supplyto increase power applied to the light source to approximately 75 Watts(step 206).

After the light source has been powered up, the microcomputer directspositioning table 20 to move head 18 to a predetermined "home" position(step 208), where the light path between head 18 and photodetector 52 isunobstructed by microplate 22. Calibration of photodetectors 48 and 52is then performed for absorbance measurements.

Following photodetector calibration, microcomputer 46 directs table 20to move head 18 such that samples located in specified wells 23 ofmicroplate 22 are scanned (step 210). As table 20 moves head 18(typically in a push-pull fashion), it does not interfere with fibers40, 54, 56, and 58. During a scan, signals of photodetector 72 and/orphotodetectors 48 and 52 are processed by the microcomputer to measureone or more of absorbance, fluorescence, and luminescence of the analytesamples.

Depending on the instructions received during step 202, themicroprocessor either repeats the scan (step 210) or switches the lightsource to idle mode (step 200).

Because of the optical coupling provided by movable arm 12, bending andtwisting of optical fibers during the scanning procedure is eliminated.Thus, the optical energy path through each fiber remains constant, sothat measurements produced during a scan are consistent from sample tosample. Moreover, measurements from one scan to another are fullyrepeatable. Additionally, since cyclical bending of fibers does notoccur, quartz optical fibers can be used to perform spectroscopicanalyses in the ultraviolet region of the spectrum.

Thus, it has been shown that we have provided a multi-functionalphotometer which measures absorbance, fluorescence, and luminescence ofa sample; which provides repeatable measurements and produces consistentreadings between different test sites; which eliminates recurringbending of optical fibers and mechanical failure thereof; which utilizesoptical radiation ranging from the ultraviolet to the infrared spectrum;which is able to carry out kinetic measurements; which can accommodatemicroplates with different well configurations; and which is relativelysimple and inexpensive to manufacture.

Although the multi-functional photometer has been shown and described inthe form of specific embodiments, its configurations and materials aregiven only as examples, and many other modifications of the apparatusare possible. For example, the photodetectors utilized in the opticalsystem may be executed as photoemissive tubes, photomultiplier tubes,photodiodes, etc. A prism, as well as a filter, may be used to disperselight instead of a diffraction grating. Light sources, such as xenonflash lamps, tungsten-halogen lamps, and mercury vapor lamps may beemployed with the optical system of the apparatus. Liquid-filled opticalfibers may replace glass and plastic fibers. Optical-fiber couplers andintegrator may be made of a plurality of opaque materials and may havedifferent configurations. For instance, the optical fiber integrator mayaccommodate a multiplicity of fibers. Moreover, a coupling with twointegrators may be used to optically interconnect two pluralities offibers. Additionally, an axial positioning scale may take place of theCartesian-coordinate positioning table. Instead of microplate wells,analyte samples may be placed in membranes or gels. It will also beappreciated that the photometer may be operated without computercontrol, as in the case of numerous prior-art photometers that do notrequire such control.

Therefore, the scope of the invention should be determined, not by theexamples given, but by the appended claims and their equivalents.

What we claim is:
 1. A photometer utilizing light-transmitting conduitsfor analyzing optical properties of at least one analyte sample, saidphotometer comprising:an optical system having a plurality of lenses;and a scanner for reading said at least one analyte sample, said scannerbeing optically coupled with said optical system by saidlight-transmitting conduits having fixed individual shapes, said scannerincluding a linkage supportingly routing said light-transmittingconduits and maintaining said fixed individual shapes of saidlight-transmitting conduits as said scanner scans said at least oneanalyte sample.
 2. The photometer of claim 1 further including a logicfor controlling said scanner and said optical system.
 3. The photometerof claim 2 wherein said logic comprises a computer.
 4. The photometer ofclaim 1 wherein said scanner further comprises:a housing capable ofsupporting a structure for holding said at least one analyte sample; apositioning device coupled to said housing; and a first optical scanningelement coupled to said positioning device, said first optical scanningelement optically coupled with said optical system by a firstarrangement of said light-transmitting conduits, said positioning devicecapable of imparting scanning movements to said first optical scanningelement in order to scan said at least one analyte sample.
 5. Thephotometer of claim 4 wherein said positioning device is aCartesian-coordinate positioning table controlled by a computer.
 6. Thephotometer of claim 4 wherein said linkage is a movable arm comprising:afirst rigid member pivotally attached to said housing at a first axis; asecond rigid member pivotally attached to said first rigid member at asecond axis and having a first beam, said first optical scanning elementattached to said first beam; couplings for optically and pivotallyinterconnecting said light-transmitting conduits, said couplingsdisposed along said first and said second axes on said first and saidsecond rigid members.
 7. The photometer of claim 6 wherein said secondrigid member further includes a second beam, said scanner furthercomprising a second optical scanning element coupled to said secondbeam, said first and said second optical scanning elements sharing anoptical axis.
 8. The photometer of claim 7 wherein said second opticalscanning element comprises a photodetector.
 9. The photometer of claim 7wherein said second optical scanning element is optically coupled to alight-dispersing device by a second arrangement of saidlight-transmitting conduits having fixed individual shapes, said secondarrangement of said light-transmitting conduits supported by saidmoveable arm and optically interconnected by said couplings.
 10. Thephotometer of claim 9 wherein said light-dispersing device comprises adiffraction grating.
 11. The photometer of claim 9 wherein said secondoptical scanning element comprises a lens.
 12. The photometer of claim 6wherein said couplings comprise conduit couplers arranged in pairs, eachof said conduit couplers having a through aperture, each of said throughapertures housing an end of one of said light-transmitting conduits, thethrough apertures of each said pairs of conduit couplers being collinearand optically interconnecting the ends of the light-transmittingconduits inserted therein.
 13. The photometer of claim 12 wherein eachof said conduit couplers has a symmetry axis, is substantiallycylindrical in shape, and is made of an opaque material, the throughaperture of each said conduit coupler being cylindrical.
 14. Thephotometer of claim 12 wherein said couplings further include at leastone coupling comprising one of said conduit couplers paired with aconduit integrator having a through aperture that houses ends of aplurality of said light-transmitting conduits contiguous with a segmentof light-transmitting conduit, said through apertures of said conduitintegrator and said conduit coupler being collinear, said segment oflight-transmitting conduit optically coupling said ends of saidlight-transmitting conduits with the end of the light-transmittingconduit inserted into the through aperture of said conduit coupler. 15.The photometer of claim 14 wherein said plurality of light-transmittingconduits is three.
 16. The photometer of claim 14 wherein said conduitintegrator has a symmetry axis, a substantially cylindrical shape, andis made of an opaque material, said through aperture of said conduitintegrator having a substantially cylindrical shape.
 17. The photometerof claim 4 wherein said first optical scanning element comprises a bodyhaving a through bore and a plurality of through cavities surroundingsaid through bore, said through bore housing at least one of saidlight-transmitting conduits, said plurality of through cavitiesaccommodating a corresponding plurality of said light-transmittingconduits.
 18. The photometer of claim 17 wherein each of said pluralityof through cavities is formed obliquely with respect to said symmetryaxis.
 19. The photometer of claim 17 wherein said plurality of throughcavities is three.
 20. The photometer of claim 17 wherein said body ismade of an opaque material, said body having a substantially cylindricalshape and a symmetry axis, said through bore further housing a lens. 21.The photometer of claim 1 wherein said optical system further includes:alight source; and a power supply for energizing said light source, saidpower supply being controlled by a computer.
 22. The photometer of claim21 wherein said light-source is a xenon arc lamp and said power supplyis a direct-current power supply.
 23. The photometer of claim 1 whereinsaid light-transmitting conduits comprise optical fibers.
 24. Thephotometer of claim 23 wherein said optical fibers are made of quartz.25. The photometer of claim 1 wherein said optical properties are atleast one of absorbance, fluorescence, and luminescence.
 26. Aphotometer for measuring optical properties of at least one analytesample, said photometer comprising:an optical system having a pluralityof lenses; and a scanning mechanism comprising:a housing capable ofsupporting a structure for holding said at least one analyte sample; apositioning device coupled to said housing; a first optical scanningelement coupled to said positioning device, said first optical scanningelement being optically coupled to said optical system by a plurality ofoptical fibers, said positioning device capable of imparting scanningmovements to said first optical scanning element in order to scan saidat least one analyte sample, said plurality of optical fibers havingfixed individual shapes; and a movable linkage coupled to said housingand to said first optical scanning element, said movable linkagesupportingly routing said plurality of optical fibers for maintainingsaid fixed individual shapes thereof as said first optical scanningelement scans said at least one analyte sample.
 27. The photometer ofclaim 26 further including a microprocessor for controlling saidpositioning device and for monitoring said optical system.
 28. Thephotometer of claim 26 wherein said plurality of optical fibers includesan input elbow fiber, an input shoulder fiber, an input housing fiber,an array of pick-up elbow fibers, a pick-up shoulder fiber, and apick-up housing fiber, each of said plurality of optical fibers having adistal end and a proximal end.
 29. The photometer of claim 28 whereinsaid movable linkage comprises:a rigid shoulder member pivotallyattached to said housing at a first axis, said housing bearing saidinput and pick-up housing fibers, said rigid shoulder member bearingsaid input and pick-up shoulder fibers; a rigid elbow member pivotallyattached to said rigid shoulder member at a second axis and having afirst beam, said first optical scanning element attached to said firstbeam, said rigid elbow member bearing said input elbow fiber and saidarray of pick-up elbow fibers, said distal end of said input elbow fiberlocated in a through bore of said first optical scanning element, saiddistal ends of said array of pick-up elbow fibers located in throughcavities surrounding said through bore; a first optical input couplingarranged collinearly with said first axis, said first optical inputcoupling optically interconnecting said input housing fiber and saidinput shoulder fiber by providing a linear light path therebetween; afirst optical pick-up coupling arranged collinearly with said firstaxis, said first optical pick-up coupling optically interconnecting saidpick-up housing fiber and said pick-up shoulder fiber by providing alinear light path therebetween; a second optical input coupling arrangedcollinearly with said second axis, said second optical input couplingoptically interconnecting said input shoulder fiber and said input elbowfiber by providing a linear light path therebetween; and a secondoptical pick-up coupling arranged collinearly with said second axis,said second optical pick-up coupling optically interconnecting saidpick-up shoulder fiber and said array of pick-up elbow fibers byproviding a linear light path therebetween.
 30. The photometer of claim29 wherein:said first optical input coupling comprises an input housingcoupler and a first input shoulder coupler each having a throughaperture collinear with said first axis, said input housing couplerrigidly attached to said housing and accommodating the distal end ofsaid input housing fiber in its through aperture, said first inputshoulder coupler rigidly attached to said shoulder member andaccommodating the proximal end of said input shoulder fiber in itsthrough aperture, said input housing and first input shoulder couplershaving facing surfaces separated by a gap to allow said shoulder memberto pivot with respect to said housing; said first optical pick-upcoupling comprises a pick-up housing coupler and a first pick-upshoulder coupler each having a through aperture collinear with saidfirst axis, said pick-up housing coupler rigidly attached to saidhousing and accommodating the distal end of said pick-up housing fiberin its through aperture, said first pick-up shoulder coupler rigidlyattached to said shoulder member and accommodating the proximal end ofsaid pick-up shoulder fiber in its through aperture, said pick-uphousing and first pick-up shoulder couplers having facing surfacesseparated by a gap to allow said shoulder member to pivot with respectto said housing; said second optical input coupling comprises a secondinput shoulder coupler and an input elbow coupler each having a throughaperture collinear with said second axis, said input shoulder couplerrigidly attached to said shoulder member and accommodating the distalend of said input shoulder fiber in its through aperture, said inputelbow coupler rigidly attached to said elbow member and accommodatingthe proximal end of said pick-up elbow fiber in its through aperture,said second input shoulder and input elbow couplers having facingsurfaces separated by a gap to allow said elbow member to pivot withrespect to said shoulder member; said second optical pick-up couplingcomprises a second pick-up shoulder coupler and a pick-up fiberintegrator each having a through aperture collinear with said secondaxis, said second pick-up shoulder coupler being rigidly attached tosaid shoulder member and accommodating the distal end of said pick-upshoulder fiber in its through aperture, said pick-up fiber integratorrigidly attached to said elbow member and accommodating the proximalends of said array of pick-up elbow fibers contiguously arranged with anoptical fiber segment in its through aperture, said second pick-upshoulder coupler and said pick-up fiber integrator having facingsurfaces separated by a gap to allow said elbow member to pivot withrespect to said shoulder member.
 31. The photometer of claim 29 whereinsaid rigid elbow member further includes a second beam bearing a secondoptical scanning element, said first and second optical scanningelements sharing an optical axis.
 32. The photometer of claim 31 whereinsaid second optical scanning element comprises a photodetector.
 33. Thephotometer of claim 31 wherein said second optical scanning element isoptically coupled to a light-dispersing device by a second plurality ofoptical fibers.
 34. The photometer of claim 33 wherein said secondoptical scanning element comprises a lens.
 35. The photometer of claim33 wherein said second plurality of optical fibers comprises:an opticalhousing fiber supported by said housing and having a fixed shape; anoptical shoulder fiber supported by said shoulder member and having afixed shape, said optical shoulder fiber optically interconnected withsaid optical housing fiber by a first optical coupling, said firstoptical coupling providing a linear light path between said opticalhousing fiber and said optical shoulder fiber, said first opticalcoupling arranged collinearly with said first axis; and an optical elbowfiber supported by said elbow member and having a fixed shape, saidoptical elbow fiber optically interconnected with said optical shoulderfiber by a second optical coupling, said second optical couplingproviding a linear light path between said optical shoulder fiber andsaid optical elbow fiber, said second optical coupling arrangedcollinearly with said second axis.
 36. The photometer of claim 35wherein:said first optical coupling comprises a housing coupler and afirst shoulder coupler each having a central through aperture collinearwith said first axis, said housing coupler rigidly attached to saidhousing and accommodating the distal end of said optical housing fiberin its central through aperture, said first shoulder coupler rigidlyattached to said shoulder member and accommodating the proximal end ofsaid optical shoulder fiber in its central through aperture, saidhousing and first shoulder couplers having facing surfaces separated bya gap to allow said shoulder member to pivot with respect to saidhousing; and said second optical coupling comprises a second shouldercoupler and an elbow coupler each having a central through aperturecollinear with said second axis, said second shoulder coupler rigidlyattached to said shoulder member and accommodating the distal end ofsaid optical shoulder fiber in its central through aperture, said elbowcoupler rigidly attached to said elbow member and accommodating theproximal end of said optical elbow fiber in its central throughaperture, said second shoulder and elbow couplers having facing surfacesseparated by a gap to allow said elbow member to pivot with respect tosaid shoulder member.
 37. The photometer of claim 26 wherein saidoptical system further includes a light source energized by acomputer-controlled power supply.
 38. The photometer of claim 37 whereinsaid light source is a xenon arc lamp.
 39. The photometer of claim 26wherein said optical properties are at least one of absorbance,fluorescence, and luminescence.
 40. The photometer of claim 26 whereinsaid positioning device comprises a Cartesian-coordinate positioningtable.
 41. The photometer of claim 26 wherein said first opticalscanning element comprises a body having a symmetry axis, a throughbore, and through openings surrounding said through bore.
 42. Thephotometer of claim 41 wherein said body has a substantially cylindricalshape, said through bore housing a lens, said through openings beingequidistant from each other and from said symmetry axis, said throughopenings being formed obliquely with respect to said symmetry axis. 43.A photometer utilizing light-transmitting paths for analyzing opticalproperties of at least one analyte sample, said photometer comprising:anoptical system; and a scanner for reading said at least one analytesample, said scanner being optically coupled with said optical system bysaid light-transmitting paths having fixed individual shapes, saidscanner including a moveable arm supportingly routing saidlight-transmitting paths and maintaining said fixed individual shapes ofsaid light-transmitting paths as said scanner scans said at least oneanalyte sample.
 44. The photometer of claim 43 wherein said scannerfurther comprises:a housing capable of supporting a structure forholding said at least one analyte sample; a positioning device; and afirst optical scanning element coupled to said positioning device, saidfirst optical scanning element optically coupled with said opticalsystem by a first arrangement of said light-transmitting paths, saidpositioning device capable of imparting scanning movements to said firstoptical scanning element in order to scan said at least one analytesample.
 45. The photometer of claim 44 wherein said linkage is amoveable arm comprising:a first rigid member pivotally attached to saidhousing at a first axis; a second rigid member pivotally attached tosaid first rigid member at a second axis and having a first beam, saidoptical scanning element attached to said first beam; couplings foroptically and pivotally interconnecting said light-transmitting paths,said couplings disposed along said first and said second axes on saidfirst and said second rigid members.
 46. The photometer of claim 45wherein said second rigid member further includes a second beam, saidscanner further comprising a second optical scanning element coupled tosaid second beam, said first and said second optical scanning elementssharing an optical axis.
 47. The photometer of claim 46 wherein saidsecond optical scanning element is optically coupled to alight-dispersing device by a second arrangement of saidlight-transmitting paths having fixed individual shapes, said secondarrangement of said light-transmitting paths supported by said moveablearm and optically interconnected by said couplings.